When electric characteristic inspection is performed on an object to be inspected, such as a semiconductor wafer, by using a plurality of probes, for example, tips of the probes provided at a probe card are imaged by using a camera to detect tip positions of the probes, and the probes are made into contact with electrode pads of the object, thereby implementing the inspection. The detection of the tip positions of the probes using a camera requires time for the camera to focus on the probe tips. Consequently, a long time is inevitably required to align the object and the probe card. Thus, conventionally, for example, the alignment has been implemented on some selected probes, rather than being implemented on all the probes.
However, in case of microelectrode pads, all the probes may not sufficiently contact the respective electrode pads and, thus, it is preferable to detect tip positions of all the probes if possible. Moreover, there may be a deviation in manufacturing probe cards and it is difficult to avoid such a deviation in manufacturing even the same type of probe cards. Thus, it requires further accurate detection of the probe tips.
Further, since probe card makers have developed various kinds of probe cards, it is necessary to develop an exclusive algorithm to perceive a three-dimensional image of probes whenever using any one of the probe cards. Since it takes enormous costs to develop such an exclusive algorithm, a technology for transferring an image of probes onto a two-dimensional film is required to facilitate the development of the algorithm.
For example, Patent Document 1 discloses a probing method for aligning probes and a wafer. In the disclosed method, needle marks are transferred onto an aligned wafer on a table, or a sheet additionally provided at the table, and a direction of the wafer is compared with a direction of the probes, to correct a direction of the table. Thereafter, an operation for aligning XY coordinates of a reference chip of the wafer with XY coordinates of the probes is carried out.
Patent Document 2 discloses a method for detecting states of tips of probes by using a transfer sheet. In the disclosed method, thermally expanded probes are made into press contact with a transfer sheet disposed on a supporting member next to a mounting table, thereby forming needle marks on the transfer sheet. Then, after detecting the needle marks on the transfer sheet, the thermally expanded probes are aligned with a wafer.
Patent Document 3 discloses a position alignment method. In the disclosed method, a direction and set positions of probes are perceived by detecting needle marks formed on a dummy wafer by using a camera.
However, Patent Document 1 does not disclose detection of probe tips as an important alignment factor. In Patent Document 2, XY coordinate data of the probes are acquired based on the needle marks formed on the transfer sheet. However, a depth of the needle marks should be detected to detect a height of probe tips and, thus, it is difficult to detect the height of the probe tips with a high accuracy. Further, in Patent Document 3 in which tip positions of probes are detected based on the needle marks formed on the dummy wafer, although XY coordinate data of probe tips can be acquired in the same way as the technology of Patent Document 2, Z coordinate data of the probe tips can be acquired only by using a camera.
To solve the above-described problems, the applicant of the present invention has proposed a method for detecting tip positions of probes with a high accuracy as disclosed in Patent Document 4. The conventional probe tip position detecting method will be explained in brief with reference to FIGS. 10A to 10G. In the conventional method, first, as shown in FIG. 10A, an upper CCD camera 1, which is provided at an alignment bridge of an alignment device (not shown), and a lower CCD camera 3, which is provided at a side of a mounting table 2, are focused on a target 4 installed to the mounting table 2, to obtain a reference position of the mounting table 2. Next, as shown in FIG. 10B, during movement of the mounting table 2, the upper camera 1 searches a tip position detecting device 6 used to detect tips of probes 5A of a probe card 5, and detects a position of an upper surface of the tip position detecting device 6, thereby acquiring x, y and z positions of the upper surface of the tip position detecting device 6 based on a position of the mounting table 2 at the time of detection. Thereafter, as shown in FIG. 10C, the lower CCD camera 3 detects a tip position of a dummy pin 7 provided at the alignment bridge. Continuously, as shown in FIG. 10D, the dummy pin 7 is made into contact with the tip position detecting device 6, the position of the upper surface of which was detected, to check whether or not the tip position detecting device 6 operates normally. If the tip position detecting device 6 operates normally, as shown in FIG. 10E, the position of the upper surface of the tip position detecting device 6 is detected again. After detecting the position of the upper surface of the tip position detecting device 6, as shown in FIG. 10F, the probes 5A of the probe card 5 are made into contact with the upper surface of the tip position detecting device 6, so that the tip position detecting device 6 detects x, y and z positions of tips of the probes 5A based on the position of the mounting table 2. Then, the mounting table 2 is moved by targeting the x, y and z positions of the tips of the probes 5A detected by the tip position detecting device 6, allowing the lower CCD camera 3 to rapidly detect the tips of the probes 5A with a high accuracy. In this case, the lower CCD camera 3 can be easily focused on the tips of the probes 5A because the positions of the tips of the probes 5A are already detected and known.
Although the technology of Patent Document 4 enables high accuracy detection of tip positions of the probes 5A, this detection requires many processes as shown in FIGS. 10A to 10F until detection of the probes 5A is completed. Therefore, a long time is inevitably required to detect the tip positions of the probes 5A.
[Patent Document 1] Japanese Patent Publication No. H5-067059
[Patent Document 2] Japanese Patent Laid-open Application No. 2005-079253
[Patent Document 3] Japanese Patent Laid-open Application No. H2-224260
[Patent Document 4] Japanese Patent Laid-open Application No. 2007-324340